katastello describes quieting a crowd or being kept quiet so that reckless action does not follow.

The attested use concerns bringing a crowd to quiet and the resulting state of restraint: the town clerk quiets the crowd in Acts 19:35, and the people are urged to remain quiet rather than act recklessly in Acts 19:36.

1. Quieting and remaining restrained · dominant

   In Acts 19:35, the aorist active participle describes the town clerk after he has addressed the crowd; the APB renders the clause "when the town clerk had quieted the crowd." In Acts 19:36, the perfect passive participle occurs in the instruction that the hearers be quiet and not do anything reckless; the APB renders, "it is necessary that you be quiet and do nothing reckless."

   Acts 19:35Acts 19:36

In the Anselm Project Bible: The APB presents the term through "had quieted the crowd" in Acts 19:35 and through the call to "be quiet" in Acts 19:36. These are verse-level renderings rather than definitions.